Whole cereal grains are nutritious and provide a high dietary fiber content. Shredded products have been historically made with whole grain wheat. Generally, in the production of shredded wheat ready-to-eat cereal biscuits and shredded wheat wafers from whole grains, a plurality of shredded layers are laminated upon one other, and the laminate is cut, dockered, and baked to provide products having a distinctly visible shred pattern on their opposing major surfaces. The shreds provide visual attractiveness and a unique, crispy texture and connote a healthy, hearty, natural product. Also, the shreds provide increased surface area and deliver a robust flavor.
To prepare wheat for shredding, whole wheat berries are generally cooked and then tempered, using prolonged tempering times. Wheat is generally easy to shred over long periods after the cooking and tempering, for example up to about 24 hours after tempering. Whole wheat is unique in that it contains gluten which helps to retain water and to provide cohesiveness and elasticity during machining even after prolonged periods after tempering. However, the same is not true for other grains because of their lack of gluten and their unique chemical composition and changes that happen to the grains after cooking and tempering.
Starch-based compositions which have little or no gluten, when mixed with water, tend not to form a dough that is cohesive at room temperature and continuously machinable or sheetable. Machinability of dough made from ingredients having little or no gluten may be improved by forming a dough under elevated temperature conditions, such as by steaming the ingredients, as disclosed in U.S. Pat. Nos. 4,873,093 and 4,834,996 to Fazzolare et al. However, in the production of shredded products from cooked, tempered, non-glutenous whole grains such as corn, oats, rye, and barley, shreddability into long continuous shreds tends to decrease as tempering times increase or as the time between tempering and shredding increases. For example, cooked corn has a tendency to become hard and rubbery during the cooling and tempering process due, it is believed, to starch retrogradation. Also, storing of tempered corn in surge bins to accommodate mass production processes tends to increase starch retrogradation and hardness. The cooked, tempered cereal grains which become hardened or rubbery, tend to fracture during shredding or do not conform to shredding roll grooves for producing continuous, well-defined shredded net-like sheets.
In conventional processes for producing shredded cereals, the grain is cooked and then permitted to temper to increase shred strength. Tempering of the cooked grains prior to shredding has generally been considered necessary for obtaining strong, continuous shreds. In U.S. Pat. Nos. 548,086 and 1,159,045, cooked wheat or similar grains are subjected to tempering times of over 12 hours before shredding. As described in U.S. Pat. No. 4,179,527, in the manufacture of a whole wheat food product such as shredded wheat, whole wheat is cooked sufficiently to gelatinize the starch. Gelatinization is a function of water penetration into the whole berry, temperature, and time, for a given type of grain. According to U.S. Pat. No. 4,179,527, the gelatinization of wheat starch involves a destruction of bonds in the crystalline regions of starch granules. Retrogradation is the return of the starch molecules to a crystalline structure, which is different from the original crystalline structures, upon cooling. Tempering permits the gelatinized wheat starch to slowly cool and permits water migration through the wheat particles to achieve a uniform water distribution within the particles. Retrogradation occurs during tempering. According to U.S. Pat. No. 4,179,527, if shredding is attempted shortly after cooking, the insufficient degree of retrogradation or tempering results in at best, short noncontinuous strands and/or strands which are tough, curly, or suffer from other physical or textural disadvantage. In U.S. Pat. No. 4,179,527, the time required for the tempering of cooked whole wheat is substantially reduced by chilling the wheat at a temperature of from 1° C. to about 12° C.
It is believed that for wheat, the tempering permits distribution of water and facilitates development of the gluten into a network which provides cohesiveness for shredding. It is also believed that the retrogradation of wheat starch during tempering or after tempering is slow so as not to impede shredding or it forms a crystalline structure which permits shredding in the presence of gluten. Tempering of non-glutenous grains, such as corn, oats, rye, and barley also helps to distribute water throughout the starch granules. It is believed that release of some soluble starch during cooking and distribution of the starch and water during tempering helps to provide cohesiveness. However, the amount released may be insufficient for continuous shreddability or starch retrogradation may be too rapid and may provide a crystalline structure which impedes shreddability into long continuous shreds.
Numerous other processes for producing shredded cereal products with reduced tempering times or without any apparent tempering are also known. Shredded cereal products, whether tempering is used or not, have also been produced by shredding the cereal in a form other than its cooked berry form.
International Patent Publication Nos. WO 03/034838 A1 and WO 03/024242 A1, and U.S. Patent Application Publication No. US 2004/0166201 A1 disclose the addition of an enzyme to starch-based raw materials to accelerate the retrogradation of starch and thus allow a shortening of the tempering step in the production of snack pellets and in the production of shredded cereals.
U.S. Pat. No. 6,303,177 and European Patent Application Publication No. EP 1,132,010 A1 disclose the production of a soy containing breakfast cereal by extrusion cooking a composition containing a soy material and a cereal grain to obtain a substantially gelatinized dough. A conventional pelletizer may be used to form dough beads from the cooked dough as it is extruded from the forming extruder. The pelletizer blades cut the dough extrudate rope into beads or pellets for further processing into flakes or shredded cereal. The dough beads may be dried to a moisture content of less than 18% and then the dried beads may be tempered for about 4 hours to about 10 hours before shredding.
U.S. Pat. No. 5,368,870 discloses fortifying a ready-to-eat cereal with beta carotene by adding to cooked tempered cereal grains prior to piece forming. Tempering times may range from approximately 2 hours to approximately 36 hours. The cooked cereals pieces may comprise cooked grains or fragments such as whole wheat berries or grits, corn cones, oat flakes, and the like. After fortification, the cooked tempered cereal pieces may be formed into pellets for flaking or may be shred in shredding rolls.
U.S. Pat. No. 5,182,127 and International Patent Publication No. WO 93/05665 disclose tempering of cooked cereal pellets or pieces for ready-to-eat cereals or cereal based snack half products by exposing the pellets or pieces to a high intensity microwave field for a brief time sufficient to improve moisture distribution therein but without causing the pellets or pieces to puff. The microwave tempered pellets or pieces may be flaked or shredded.
U.S. Pat. No. 4,528,202 discloses the production of the ready-to-eat shredded potato products by combining at least one potato starch source with water under low temperature and low shear mixing conditions so as to avoid overgelatinization of the potato starch and to form individual discrete dough pieces or particles, tempering the dough pieces for at least about two hours to distribute the water substantially uniformly throughout the dough pieces, shredding the tempered dough pieces, and cooking the shredded dough.
Processes where tempering is not specifically mentioned or is indicated as being optional in the production of cereals from wheat or other grains, are disclosed in U.S. Pat. Nos. 1,189,130, 2,008,024, 1,946,803, 502, 378, 897,181, 3,062,657, 3,462,277, 3,732,109 and Canadian Patent No. 674,046.
In U.S. Pat. No. 1,189,130, thoroughly moistened bran, such as wheat bran, is mixed with up to 50% of whole wheat or other gelatinous cereal flour or starch-bearing material, and is cooked in pans in a steam retort. The cooked product is dried to a lumpy condition, the lumps are pressed through a vial mesh and the resulting rice sized lumps are then fed through shredding mills.
In U.S. Pat. No. 2,008,024, a cereal biscuit is prepared by steaming or boiling wheat alone or with other forms of cereal or food material, surface drying the cooked product, and then converting it into a thin ribbed sheet. The shredding rolls are spaced sufficiently apart so that a sheeted material with ribs is obtained instead of a shredded product.
In U.S. Pat. No. 1,946,803, rice, alone or in combination with bran, is steam cooked, dried and cooled to a rubbery consistency, ground and optionally tempered to effect a uniform water distribution. This product is then passed between grooved rollers to form long flat ribbons. These ribbons are dried to produce a brittle product which is broken and then puffed by toasting.
In U.S. Pat. No. 502,378, a cereal grain is prepared for shredding by boiling, steaming, steeping or soaking. Depending upon the spacing between the rollers, a product in the form of threads, lace, ribbons, or sheets, and the like, is obtained.
In U.S. Pat. No. 897,181, cereal grain or vegetable in whole form is wetted but not cooked and then passed repeatedly between grooved rollers and then baked. Boiling or steaming of the grain or vegetable, it is disclosed, produces considerable change in its chemical quality and a number of the nutritious soluble elements escapes to the water.
In the processes of U.S. Pat. Nos. 3,062,657, 3,462,277, and 3,732,109, and Canadian Patent No. 674,046, a shredded product is not produced by means of shredding rolls. In U.S. Pat. No. 3,062,657, flour and water are mixed to form a dough in an extruder. The dough is cooked in the extruder and then tempered in the extruder at a lower temperature. The extrudates are cut into pellets to simulate cooked and dried grains such as corn grits, whole wheat berries, oat groats, rice and the like. The extrudates, it is disclosed, have a moisture content ideal for flaking. It is generally on the order of 18 to 24% by weight, the moisture being uniformly distributed throughout so that the necessity for tempering is entirely eliminated and the extrudate can be immediately transferred to a flaking operation. It is disclosed that it is preferable to further cool the extrudate before it enters the flaking device to optimize flaking properties.
In U.S. Pat. No. 3,462,277, a mixture of cereal flour or grits and water is passed through an extruder to gelatinize the starch while the dough is cooked and transformed into a rubber-like mass. The moisture content of the mixture is 13 to 35%. The continuous U-shaped extrudate is pinched off into segments by cutting rolls to form canoe-shaped cereal products. The separated canoe-shaped pieces are then dried to below 15% moisture.
U.S. Pat. No. 3,732,109, discloses the production of a ready-to-eat oat cereal biscuit by subjecting an oat flour-water mixture to a water boiling temperature and superatmospheric pressure to gelatinize a portion of the starch in the oat flour. The mixture then passes through an orifice and the extruded product is cut into small pieces. The flake-shaped pieces which are formed are dried to a moisture content of from about 2% to about 6% by weight water. The dried flakes are then subdivided, admixed with a syrup, and compacted into the form of a biscuit. The formed biscuits are then dried to a moisture content of from about 4 to 5% by weight.
In Canadian Patent No. 674,046, a shredded dry oat cereal product is produced without the use of shredding rolls. A dough is cooked in a screw extruder, extruded through orifices to form a strand bundle, and the strand bundle is cut into pieces by a cutting device which may be a pair of rolls.
Processes for the production of shredded cereals from cereal grains wherein considerable tempering is used, as in the conventional process for the production of shredded wheat, are disclosed in U.S. Pat. Nos. 1,159,045, 1,170,162, 1,197,297, and 4,004,035. In U.S. Pat. Nos. 1,159,045, 1,170,162 and 1,197,297, the whole berry is pulverized so as to permit flavoring ingredients to be incorporated in the final product. A dough is formed from flour, flavoring, and water. The dough is then cooked, rolled into slabs and then atmospherically dried for a period of 24 to 40 hours. The dried product is toasted, broken into pea size pieces, dried and then shredded. In U.S. Pat. No. 4,004,035, shredded biscuits are formed by depositing a layer of shredded cereal in zig-zag configuration on a moving belt to facilitate severing the material. In addition to whole wheat, other foods capable of being shredded, such as other cooked cereal, wheat germ, defatted soy, other vegetable protein, fruits, vegetable slurries and mixtures thereof may be employed in producing the biscuits. The food is softened by cooking and tempering prior to shredding.
In the production of shredded cereals by means of shredding rolls, obtaining the cooked cereal in a form which will produce continuous shreds is only one of several problems which are encountered.
Cooking to eliminate white centers in grains is taught in U.S. Pat. Nos. 2,421,216 and 4,734,294. In U.S. Pat. No. 2,421,216, particles of cereal grains such as corn, rye, wheat, bran, rice, or oat groats are composited with particles of de-fatted soya beans in the form of grits, flakes, or meal to enhance the protein content of the cereal by use of a two-stage pressure cooking step. The total cooking period to which the cereal component is subjected to should, according to U.S. Pat. No. 2,421,216, be such that the starches are hydrolyzed and highly dextrinized and the particles superficially gelatinized with no free starch or white center. The cereal particles, it is taught, should also have a light adhesive action of the intermediately added soya bean particles. The mixed mass of cereal and soy which is removed from the cooker, is dried, then tempered for about 15 to 30 minutes before shredding in a shredding mill wherein the particles of soya become substantially uniformly spread out over and mixed with the cereal particles and adhered thereto by pressure through the shredding rolls.
U.S. Pat. No. 4,734,294 discloses a process for the production of shredded oat food products, such as ready-to-eat breakfast cereals having the shredded appearance and texture of shredded whole wheat. White streaks or spots in the final product, which result from uncooked grain or overcooked grain, are eliminated by pressure cooking the oats in at least two stages, the amount of water used in the first pressure cooking stage being limited to partially gelatinize the starch without substantial extraction of water soluble starches and gums to the surface of the oat particles. The amount of water used in the remaining pressure cooking stage or stages is sufficient to eliminate at least substantially all of the white portions in the oat particles and to provide a water content in the oat particles which is sufficiently high to enable continuous shredding on shredding rollers. Additionally, the amount of water in each of the remaining stages is limited to avoid substantial extraction of the gums and water soluble starches to the surface of the partially cooked oat particle.
In U.S. Pat. No. 3,512,990 a dough, made from farinaceous materials such as wheat, corn, oats, rice, potatoes, or legumes, is optionally partially or completely cooked with added moisture, to an approximate moisture content of about 30%. After this cooking step, the mixture is rendered homogeneous by passing it through an extruder or a hammer mill, such as Fitzmill. The milled or extruded product is dried to an approximate moisture content of 22 to 24%. The dried dough is then compacted between two rolls to provide a shredding effect and produce a sheet of dough having diamond-like regularly spaced perforations. The sheet of dough is then severed into strips, folded to form small biscuits which are closed on three sides and then deep fried.
In U.S. Pat. Nos. 987,088, 1,019,831, and 1,021,473, corn or another grain is ground and immersed in an amount of water which is limited to that which will be taken up by the grain during cooking. The purpose of this is to preserve in the cooked article the aroma and other properties of the grain which might otherwise be carried off or dissipated by the evolution of steam or vapor. In these processes, the cooked dough is extruded through a perforated plate to obtain filaments.
In U.S. Pat. No. 4,310,560 particulate edible materials, including at least one material which acquires surface stickiness when moistened and a chemical leavening system are contacted with a spray of water and formed into pellets on a pelletizing disk. The edible material may include starches, such as those derived from wheat, corn, rice, potatoes, tapioca, and the like, including pregelatinized starches. The pellets are heated to a temperature sufficient to effect reaction of the leavening system to release carbon dioxide to provide the pellets with a porous cellular structure.
The present invention provides a method for the continuous, mass production of 100% whole grain food products such as ready-to-eat cereals and thin, crispy, chip-like snacks in shredded form from non-glutenous or low-gluten content whole grains such as corn, barley, rice, rye, oats, triticale, and mixtures thereof. The cooked, tempered whole grains are continuously shreddable into continuous net-like sheets even after prolonged tempering times or after prolonged periods in surge vessels after tempering during which substantial starch retrogradation may occur. The method of the present invention permits the use of fully cooked, tempered, but fracturable, hardened, rubbery whole cereal grain pieces in the continuous production of shredded products while achieving well defined shreds and a crisp texture and high fiber content. It is believed that in the process of the present invention, fracturing of at least substantially gelatinized, tempered starch granules to release amylose and amylopectin increases cohesiveness and softens whole cereal grain pieces for unexpectedly superior shreddability into continuous net-like sheets. Whole wheat shredded products having an enhanced crispy texture may also be produced using short temper times with excellent shreddability in accordance with the present invention.